I attempted to create an entry for a Rhododendron plant, Southgate Azalea (Breeze 'Janet Blair') and got the message that the plant is already in the database here Rhododendron Southgate® Breeze™
Now I see that I have to look into this further. It's possible that Southgate is the series name and the others are trade names. I have a medical appointment this morning, so I'll look into it when I return.